The present invention is a storm water filter system which includes a filter and filter box for filtering drain water before directing the water into an outlet for discharging the filtered storm water. More specifically, the present invention is directed towards a filter box skimmer for preventing floatable trash and floatable oil from entering the outlet from the filter box.
Drain water, which is frequently laden with trash, grass clippings, tree limbs, sand, gravel and other forms of sediment, as well as floatable trash and floatable oil is collected from streets, parking lots and other areas into a storm drain inlet where it is directed into a storm drain pipe system. The drain water laden with trash collected from the streets is fed through an entrance into a storm water catch basin and into a lake or retention pond. The retention pond can tolerate a certain amount of grass clippings collected from parking lots along the streets but debris left in water for a long period of time decays and allows a build up of soluble nutrients, such as nitrates and phosphates to accumulate in the water. Thus, it is desirable to remove organic debris from the water collected from the drain water before it enters lakes and retention ponds. At the same time, drain water collects residue oil, and floatable hydrocarbons and organic materials from parking lots and streets and it is also desirable to prevent the floating hydrocarbons being discharged into the lakes or retention ponds. Typically, a skimmer is utilized to capture hydrocarbons and floating liquids within a baffle box to prevent their passing into the outlet.
The present invention is directed towards a skimmer to prevent floatable trash and floatable hydrocarbons from passing out the outlet of a storm water drain system baffle box.
In my prior U.S. Pat. No. 6,869,525 for a Storm Drain Filter System I show a storm drain filter system which includes a skimmer for collecting floating hydrocarbons and for absorbing the hydrocarbons in a hydrocarbon absorbing boom while preventing them from passing out of the skimmer. In my prior U.S. Pat. No. 7,294,256 for a Storm Water Filter System, a storm water filter system is provided for filtering storm water being fed into an in-ground well and uses a fixed skimmer to prevent floating organic debris from entering the discharge into the in-ground recharge well.
The present invention is directed towards an improvement in storm water filter systems and filter boxes in which the filter box has a skimmer protecting the outlet from the baffle box of hydrocarbons and floating oil and the like. Drain water entering a baffle box sometimes flows in very fast and allows the water to rise above a fixed skimmer. This allows floating trash and floating oil and hydrocarbons to go over the top of the skimmer and out the outflow pipe into rivers, lakes or retention ponds. The present invention provides for a floating skimmer that prevents this overflow and forces the drain water existing the baffle box to go under the skimmer and out the outlet.
A relative short skimmer that floats will have the same performance of a much taller fixed skimmer without the head loss associated with a taller skimmer. A storm water treatment structure that makes use of a floating skimmer can be more easily retrofitted to an existing water shed storm drain system due to the minimal head loss of the shorter skimmer.